Smartphone Button Hack

# run this command as root on the smartphone

getevent -l
...

add device 7: /dev/input/event8
  name:     "Midas_WM1811 Midas Jack"

add device 8: /dev/input/event1
  name:     "gpio-keys"

# list key presses of the headset button

getevent -t -l /dev/input/event8

[   16116.002037] EV_KEY       KEY_MEDIA            DOWN
[   16116.002069] EV_SYN       SYN_REPORT           00000000
[   16116.213047] EV_KEY       KEY_MEDIA            UP
[   16116.213087] EV_SYN       SYN_REPORT           00000000

# filter output of getevent

getevent -t -l /dev/input/event8 | grep KEY_MEDIA

cat > stdbuf.c<<EOF
#include <stdio.h>

__attribute__ ((constructor)) void
stdbuffer () {
  setvbuf (stdout, NULL, _IOLBF, 0);
}
EOF

arm-linux-androideabi-gcc -Wall -x c -s stdbuf.c -fPIC -shared -o stdbuf.so

# copy stdbuf.so to the smartphone from the computer:

wget https://www.torsten-traenkner.de/cyanogenmod/hacks/stdbuf.so
adb root
adb push stdbuf.so /data/media/0/stdbuf.so
adb shell "chmod 755 /data/media/0/stdbuf.so"

# log in to the smartphone
adb shell

# run unbuffered getevent:
LD_PRELOAD=/data/media/0/stdbuf.so getevent -t -l /dev/input/event8 | grep KEY_MEDIA

[   18500.420251] EV_KEY       KEY_MEDIA            DOWN
[   18501.548734] EV_KEY       KEY_MEDIA            UP

# copy headset.sh to the smartphone:

wget https://www.torsten-traenkner.de/cyanogenmod/hacks/headset.sh
adb push headset.sh /data/media/0/headset.sh
adb shell "chmod 755 /data/media/0/headset.sh"

# create alias for start and stop of the script
cat > alias.txt<<EOF
alias he='/data/media/0/headset.sh </dev/null >/dev/null 2>&1 &'
alias hestop='bash /data/local/tmp/headset.pid ; rm /data/local/tmp/headset.pid'
EOF

adb push alias.txt /data/media/0/alias.txt
adb shell "cat /data/media/0/alias.txt >> /data/media/0/.bashrc"

#!/system/xbin/bash

#
# Shell script to handle the key presses of a headset button.
# Works on CyanogenMod and maybe rooted Android.
#
# Precondition: disable the headset button function with Xposed Additions.
#   see: http://repo.xposed.info/module/com.spazedog.xposed.additionsgb
#
# Author: Torsten Tränkner
# License: GPLv3
#

# save the process id to kill the process later
echo "Own process id: $$"
mkdir -p /data/local/tmp/
echo "pkill -9 -P $$; kill -9 $$" >> /data/local/tmp/headset.pid

# 0.25 seconds for long key press
THRESHOLD_LONG_PRESS=250000

# seconds for timeout after key press
THRESHOLD_TIMEOUT="0.3"

HEADSET_BUTTON_DEVICE=/dev/input/event8

function main() {

  createNecessaryFiles

  echo "Start headset button event handling."

  codeString=""

  while true; do

    # read from file descriptor of the fifo
    read $TIMEOUT line <&3

    # check for timeout of read
    if [ $? -eq 142 ];then
      echo "Timeout"
      TIMEOUT=""

      echo "$codeString"

      # s is short press, l is long press

      case $codeString in
        s)
          echo "Media play / pause"
          input keyevent KEYCODE_MEDIA_PLAY_PAUSE
          ;;
        ss)
          echo "Volume down"
          input keyevent KEYCODE_VOLUME_DOWN
          ;;
        sss)
          echo "Volume up"
          input keyevent KEYCODE_VOLUME_UP
          ;;
        ls)
          echo "Next song"
          input keyevent KEYCODE_MEDIA_NEXT
          ;;
        sl)
          echo "Previous song"
          input keyevent KEYCODE_MEDIA_PREVIOUS
          ;;
        lss|ssss)
          echo "Volume up up"
          input keyevent KEYCODE_VOLUME_UP KEYCODE_VOLUME_UP
          ;;
        ssl)
          echo "Volume down down"
          input keyevent KEYCODE_VOLUME_DOWN KEYCODE_VOLUME_DOWN
          ;;
        *)
          echo "Unkown combination."
          ;;
      esac

      codeString=""

    else

      if [[ "$line" =~ .*"KEY_MEDIA            DOWN".* ]]; then
        #echo "$line"
        pressedDownTime=$(getTime "$line")
        TIMEOUT=""

      elif [[ "$line" =~ .*"KEY_MEDIA            UP".* ]]; then
        pressedUpTime=$(getTime "$line")
        timeDifference=$(expr $pressedUpTime - $pressedDownTime)

        # check for short or long key press
        if [ $timeDifference -lt $THRESHOLD_LONG_PRESS ];then
          echo "short press. $timeDifference"
          codeString+="s"
        else
          echo "long press. $timeDifference"
          codeString+="l"
        fi

        # start timeout for the next keypress
        TIMEOUT="-t $THRESHOLD_TIMEOUT"
      fi

    fi

    if [ $finished == true ]; then
      echo "Finished"
      exit 0
    fi

  done
}

# get time in microseconds from event string
function getTime() {
  echo "$1" | sed 's|^\[ *\([0-9]*\)\.*\([0-9]*\)\].*|\1\2|g'
}

function createNecessaryFiles() {

  # create fifo (first in first out) for the events
  mkfifo /data/button.fifo > /dev/null 2>&1

  # create binary "unbuffer" program
  # source code see below
  if [ ! -e /data/media/0/stdbuf.so ];then

    echo "QlpoOTFBWSZTWSuU0FkAAwJ///////5h9054L+c2\
MP/n/3LsRtRFwFRUBwkQRABa+GBw0AMisKoajAaa\
kxCU9TMymnppEHqNNqep6TT1NMmho9QNGnqeoADQ\
0eptJtIPUMgAzUNlPU9QaiYTUwp6ZAgBoAAAAAAA\
AAAAANA0AAABIkgSbSIDEADQMgDTQYQDIaGgANAa\
AAAAGhoBBgCYTAmEwmmCYjAEwBGhkwCYAAABGAmA\
AAQYAmEwJhMJpgmIwBMARoZMAmAAAARgJgAAGNda\
K9cFEUCQ8DA/IBURwo+44/rw4/ljzl5E/CwKnK3M\
B3dZq9GcJ7o0ONltz4nqtOTwMbAhU6gA+2Dw2z31\
0aGHQi3CBKEhZkBR3TFSvg5xdCjBSlhsooiVsmSn\
J48qDg4dKRLnZkypFj0HqGU7HCw4VW7bTkwvNRGJ\
RVcZDzylFUYss5Ovq0xwq1XMeci2Vw2HXg9jaDNr\
SN1uRC/NZm1FL81rX91ObNxQ/Zyol40YAslBCQFG\
eQEEZAA1FmAqczCGCUMJDEWnDCGoczRXPA7EMe6o\
dMSCRTEzmbY2YLpchk8QDaBzwqWXvzrkqLaKHDJM\
UMCpohyiIcOTW7YsVrJYAF80BtHU75gjTtNpDlCI\
YFLtNIC+YZKUALHNOr566sjSbqWH3CNkgDLIvlEz\
NM6brFrc1dSq8mdVGTRE1vYljM7TDMu8WQCMthpk\
DCkL2CGLWNdGmFEMlRSF6PednEBK94EFSImCahhH\
yFHEWJxGSQAz6O0c91KxYZTQYJdF/Mt+y4YGhHsY\
Ihtiq+mBGXNTg38sxzMLjsQkNrVMQWmi8wD8SDVt\
XTEZj1LK2iwxbC7UNAxSbY3U0FmIAbuWDcNuzTCr\
7uVbYVVjvVIuWp/JCryoxB5TPO0m08KFZ60Hcd5F\
cSn4YTy9eN0I4lEkVPovVfcrLc0wDWUYYM3IJdjB\
1+cHEwT5NtFA5qq6CZW6M9PBf+jGiKEjImnRLqxd\
sx8SJTOcok8eXHMikIIs1Fww02CmXJ1JQwXHSliS\
aXBQ2dcyVBQFDHbRIApMrJZgHC0c5TMBCyyzbbQY\
YghgKSlwPB0OdOYyaIaCVRDmBgZ+KItPHZcLDXgA\
4MyQFUiEsRdCSP4QCSIgSZRJPRIbhILa2AmOY5So\
C2CWi5kImMRodWBJhEsil38+tVVtbSlkFaOrFthQ\
hTnVt61txjALge53LXcBTSITYIqkAYgax1egbpZ2\
GuAOlA8UT8lLwt3sVYsAp29sP7JVZI29sRpd2Abi\
r12f/bzYrRhpWpgCZsTZxIBIBAv357g8D3/F3JFO\
FCQK5TQWQA==" | base64 -d > /data/media/0/stdbuf.so.bz2

    bunzip2 /data/media/0/stdbuf.so.bz2

    chmod 755 /data/media/0/stdbuf.so
  fi

  # get events from the headset button and write them to the fifo
  # stdbuf is something like unbuffer for immediate writing, see below
  (LD_PRELOAD=/data/media/0/stdbuf.so getevent -t -l $HEADSET_BUTTON_DEVICE > /data/button.fifo) &
  shellpid=$!

  # open file descriptor 3 for reading the fifo
  exec 3</data/button.fifo

  echo "Process id to kill: $shellpid"

  finished=false

  # kill getevent and close the file descriptor of the fifo when this script is killed
  trap "kill $shellpid > /dev/null 2>&1; finished=true; exec 3>&-" 0 2 3 5 10 13 15

}

main



#####

source code of stdbuf.c

#include <stdio.h>

__attribute__ ((constructor)) void
stdbuffer () {
  setvbuf (stdout, NULL, _IOLBF, 0);
}

arm-linux-androideabi-gcc -Wall -x c -s stdbuf.c -fPIC -shared -o stdbuf.so

        ll)
          # start a playlist when headset button is pressed a bit longer twice
          echo "Start playlist"
          am start -n org.videolan.vlc/.gui.video.VideoPlayerActivity -a android.intent.action.VIEW -d /sdcard/music/playlist.m3u
          ;;